Botanists Find ‘Holy Grail’ of Georgia Grass

DNR botanist Tom Patrick at the Dichanthelium hirstii site in Sumter County.

When it comes to Hirst Brothers’ panic grass, Georgia went from zero to 500 – and from potential player to world leader – in one hot August afternoon.

A search led by Delaware Department of Natural Resources botanist Bill McAvoy and coordinated with Georgia DNR’s Nongame Conservation Section found an estimated 500 Dichanthelium hirstii plants at a limesink pond in Sumter County on Aug. 7. That marks the first time the candidate species for federal listing as endangered had been seen in Georgia since 1947, and only the third time ever.

“I was very excited,” said McAvoy, of Delaware DNR’s Species Conservation and Research Program.

McAvoy is conducting a range-wide survey of Hirst Brothers’ panic grass for the U.S. Fish and Wildlife Service. Previously, there were five known populations of the grass. That includes one plant McAvoy found in North Carolina this year, a population in Delaware and three in the New Jersey pine barrens. Of the sites in Delaware and New Jersey, only one has visible plants this year – fewer than 20 individuals.

Named for two brothers credited with discovering it in New Jersey in the 1950s, Hirst Brothers’ panic grass grows in limesink ponds, or depressional wetlands, that fill with rain in winter and go dry in summer. Thousands of these pools dot the landscape in south Georgia. But many have been altered by land uses such as farming. Others, explained DNR botanist Lisa Kruse, have been overtaken by trees and woody shrubs as the fires that kept the grasslands open have been suppressed. The habitat is also under-surveyed, particularly during the autumnal bloom phase, when the tall grass is more conspicuous.

So, while some botanists searched for the plant in Georgia, and many kept watch for it, none saw it.

McAvoy returned to Georgia this summer because the state has two historical records of Dichanthelium hirstii – from 1900 and 1947 – and the habitat considered key to the plant still seemed in place. (Both collections in Georgia were initially classified as other species, since Hirst Brothers’ panic grass wasn’t described as distinct until 1961.)

Prepping for his second trip to the state in two summers, the Delaware botanist scoured aerial photographs and maps for the signature limesink habitat. He crosschecked for sites with Boykin’s lobelia, a rare plant found alongside Hirst Brothers’ panic grass. With Kruse’s help, he focused on where the panic grass had been collected decades ago in Georgia.

And on the last day of his search in the field, and at almost the last pond, he and DNR botanist Tom Patrick found it. “It was everywhere, a clump here, a clump there,” Patrick said.

McAvoy said the population at the privately owned 10-acre pond was very healthy.

Next steps include discussions with the landowner about possible conservation options, and using habitat details from the site – the plants were found in the draw-down zone of the wet savanna habitat – to fine-tune searches on other property.

The effort is worth it, Kruse suggests.

“To the best of our knowledge, Dichanthelium hirstii is an indicator of an extremely diverse and healthy ecosystem. Often this species is also with other rare plants … So when you find it, you know that plant community is unique and intact – it’s a special place.”

Hirst Brothers’ panic grass has long been a mystery in Georgia, she said.

“It’s sort of the grass Holy Grail.”

A Grail that has been found.

(Editor’s note: Tom Patrick said there’s nothing startling in the name panic grass. Panic is based on Panus, a Latin word that can denote millet. “So it has nothing to do with what it does to taxonomists,” he said. The panic grasses are now split into two genera – Panicum and Dichanthelium – and include a few hundred species. Some are rare, while others such as switchgrass or Panicum virgatum are common.)